Z94.12.3 D - Manufacturing Automation & Computer Control

DAMPING. Refers to a characteristic built into electrical circuits and mechanical systems to prevent rapid or excessive corrections which may lead to instability or oscillatory conditions, i.e. connecting a register on the terminals of a pulse transformer to remove natural oscillations or placing a moving element in oil or sluggish grease to prevent mechanical overshoot of the moving parts.

DATA. A representation of facts, instructions, concepts, numerical and alphabetical characters, etc., in a manner suitable for communicating, interpreting, and processing by humans or by automatic means such as NC systems.

DATA FILE. A collection of related data records or application data values organized in a specific manner and stored after, and separated from, the user program area.

DATA PROCESSING. A computer procedure involving one or more operations for collecting data and producing a specified result.

DEAD BAND. A specific range of values in which the incoming signal can vary without changing the output.

DEADTIME. A definite delay between two related actions.

DEBUGGING. The process of finding and eliminating errors.

DECIBEL. A standard unit expressing a loss or gain in transmission power level. Abbreviated db. The term "DBM" is also used when a power of one milliwatt is the reference level. Db indicates the ratio of power output to power input: P 1 db = 10 log 10 P 2
DIAGNOSTIC ROUTINE. A maintenance test of key NC system components, performed by use of a special programmed tape and/or electronic instruments, to discover failure or potential failure of a machine element as well as the location of the failure. Also known as diagnostic check, diagnostic subroutine, diagnostic test, or error detection routine.

DIFFERENTIAL TRANSDUCER. A type of device which can simultaneously measure two separate stimuli and provide an output proportionate to the difference between them.

DIGIT. (1) One of the integers in a numbering system such as 0 to 9 in a decimal system. (2) A character or symbol used alone or in combination with other digits to convey a specific numerical quantity.

DIGITAL. Refers to the use of discrete integral numbers in a given base to represent all the quantities that occur in a problem or calculation. It is possible to express in digital form all information stored, transferred, processed, or transmitted by a dual-state condition (i.e., on-off, true-false, and open-closed).

DIGITAL COMPUTER. A computer which processes information represented by combinations of discrete or discontinuous data as compared with an analog computer for continuous data. More specifically, it is a device for performing sequences of arithmetic and logical operations, not only on data but also on its own program. Still more specifically it is a stored program digital computer capable of performing sequences of internally stored instructions, as opposed to calculators, such as card programmed calculators, on which the sequence is impressed manually. Related to machine, data processing.

DIGITIZE. (1) To obtain a digital representation of the value of an analog quantity. (2) To convert scaled, nonmathematical drawings or physical part dimensions to digital data. Refers to a specific device which converts an analog measurement into digital form. Syn: quantizer.

DIP (DUAL IN-LINE PACKAGE). (1) The most popular IC packaging in the mid-1970's is the plastic, dual-in-line case, using plastic for economic reasons and the dual-in-line package (DIP) configuration for manufacturing efficiently. (2) Chips are enclosed in dual in-line packages which take their names from the double parallel rows of leads which connect them to the circuit board. DIPs are sometimes called "bugs."

DIRECT MEMORY ACCESS (DMA). (1) Direct Memory Access, sometimes called data break, is preferred form of data transfer for use with high-speed storage devices such as magnetic disk or tape units. The DMA mechanism transfers data directly between memory and peripheral devices. The CPU is involved only in setting up the transfer; the transfers take place with no processor intervention on a "cycle stealing" basis. The DMA transfer rate is limited only by the bandwidth of the memory and the data transfer characteristics of the device. The device generates a DMA Request when it is ready to transfer data. (2) High-speed data transfer operation in which I/O channel transfers information directly to or from the memory. Also called "data break'' or "cycle stealing.''
DIRECT NUMERICAL CONTROL (DNC). The use of a shared computer to program, service, and log a process such as a machine tool cutting operation. Part program data is distributed via data lines to the machine tools.

DISCRETE. (1) The state of being a separate entity or having unconnected elements. (2) Pertaining to distinct elements or representation of data by means of distinct elements such as characters; pertaining to physical quantities having distinct values only.

DISK DRIVES. A typical unit consists of a drive, power supply (100-125 v AC, 60 Hz), cooling fan, disk buffer and address select electronics. It is capable of storing over 300,000 words on a flexible disk and several megabytes on a hard disk. Up to 16 disk drives can be controlled by one disk controller.

DISK STORAGE. A computer memory device capable of storing information magnetically on a disc similar in appearance to a phonograph record.

DOCUMENTATION. Manuals and other printed materials, such as tables, tape, listings, and diagrams, which provide instructive information regarding the operation, installation, and maintenance of a manufactured product.

DOWNTIME. The time period in which a system or machine tool is not available for use due to failure or routine maintenance. Also known as cumulative lost time.

DYNAMIC RAM. Data is stored capacitively, and must be recharged (refreshed) periodically (every 2 ms. or so) or it will be lost. (See RANDOM ACCESS MEMORY.)

DYNAMIC RESPONSE. The specific behavior of the output of a device as a function of the input, both with respect to time.